Molar occlusion and jaw mechanics of the Eocene primate Adapis
Version of Record online: 28 APR 2005
Copyright © 1972 Wiley-Liss, Inc., A Wiley Company
American Journal of Physical Anthropology
Volume 36, Issue 3, pages 359–368, May 1972
How to Cite
Gingerich, P. D. (1972), Molar occlusion and jaw mechanics of the Eocene primate Adapis. Am. J. Phys. Anthropol., 36: 359–368. doi: 10.1002/ajpa.1330360306
- Issue online: 28 APR 2005
- Version of Record online: 28 APR 2005
- Jaw Mechanics
Wear facets on molars of the Eocene primate Adapis magnus are described. Striations on these wear facets indicate three separate directions of mandibular movement during mastication. One direction corresponds to a first stage of mastication involving orthal retraction of the mandible. The remaining two directions correspond to buccal and lingual phases of a second stage of mastication involving a transverse movement of the mandible.
The mechanics of jaw adduction are analysed for both the orthal retraction and transverse stages of mastication. During the orthal retraction stage the greatest component of bite force is provided by the temporalis muscles acting directly against the food with the mandible functioning as a link rather than as a lever. A geometrical argument suggests that during the transverse stage of mastication bite force is provided by the temporalis muscles of both sides, the ipsilateral medial and lateral pterygoid muscles, and the contralateral masseter muscle.